After rinsing the corned beef place it on the wire rack in your Instant Pot.

Top with onion wedges and garlic.

Add liquid (water, broth, or beer).

Close and lock the lid. Select high pressure following your particular model's directions and set timer for 90 minutes.

When the corned beef is done cooking let the use a natural release for 30 minutes doing a quick-release of any remaining pressure after the cook time is complete according to the manufacturer's directions.

Unlock and remove the lid.

Using tongs, remove brisket and place on baking sheet covering with aluminum foil.

While the corned beef rests, we'll cook the vegetables.

Place the cabbage and carrots and potatoes (if desired) into the Instant Pot using the liquid that the corned beef cooked in and close and lock the lid once again.

Cook on the manual setting on high mode and set the cooking time for 5 minutes. Once done, do a quick release.

Use a slotted spoon to transfer the vegetables to a serving bowl of platter.

Slice the corned beef across the grain and serve with the vegetables.